As an example of a conventional data transfer apparatus, a data transfer apparatus positioned at the edge of a network is known that allocates a different light wavelength for each destination address contained in the IP packet, time division multiplexes the allocated light wavelengths, and transmits the optical signal that comprises the data by using the time division multiplexed light wavelength. Thereby, this data transfer apparatus transmits a large amount of data at a high speed and efficiency. (For example, refer to Japanese Unexamined Patent Application, First Publication, No. 2001-251253, paragraph 33, paragraph 43, and FIG. 10.)
As another example of a conventional data transfer apparatus, a data transfer apparatus is known in which the routing process for IP packets in which a path is determined when data is transferred based on the IP packet is integrated with the routing process for the light wavelength in which the route and the light wavelength are determined when the optical signal that comprises the data is transmitted based on the light wavelengths. (For example, refer to Japanese Unexamined Patent Application, First Publication, No. 2001-53803, paragraphs 17 and 18, and FIG. 1.)
However, currently there is the problem that a high cost for communication equipment is incurred when placing in one exchange office the communication equipment that is compatible with each of the different communication protocols related to the tunneling technologies for transferring data efficiently in accordance with the various services that provide rapidly spreading VPN (virtual private network) and VLAN (virtual local area network) and the like.
In addition, in recent years large-scale networks have been constructed by connecting the various networks operated by such different groups as industry, communication carriers and the like. Because large-scale networks are constructed by using only the high cost conventional data transfer apparatuses described above, there is the problem that the costs incurred to construct the network are high.
In contrast, conventionally MPLS (MultiProtocol Label Switching) is known as one transfer technology for IP (Internet Protocol) packets.
In networks constructed by router apparatuses that are compatible with MPLS, a label associated with the destination address of the IP packed is attached to the IP packet in an edge router apparatus. Then, a label (output label) added to a transmitted IP packet is found based on the label (input label) of the received IP packet in a core router. Finally, after swapping the label, the IP packet is transmitted to the next router apparatus, and a path is formed using the label. Note that an edge router is a router apparatus connected to a network and a terminal that are not compatible with MPLS and another MPLS network or the like (an external network), and a core router is a router apparatus that carries out the transfer of packets in the MPLS network.
In addition, a label hierarchy is created, and by referring to the labels of the same layer in the network, labeled IP packets are tunneled within the network (refer, for example, to Japanese Unexamined Patent Application, First Publication, No. 2002-44126).
However, in this type of conventional router apparatus, at the same time that the attachment and swapping of labels is carried out, it is necessary to add a switching tag to the packet in order to switch the incoming packet within the router device. This switching tag also requires searching by the destination address or the label, and thus there is the problem that the processing load increases. In addition, the cost of the router device increases due to the increase in the processing load, and thus there is also the problem that the cost of constructing the network becomes high.
Searching by destination address and adding a switching tag for switching within a router apparatus is similar to the normal transfer of IP packets.